ditokous

from The Century Dictionary.

• Producing two kinds of young, as some worms.
• In zoology, having twins; producing two at a birth; also, laying two eggs, as the pigeon and humming-bird.

from the GNU version of the Collaborative International Dictionary of English.

• adjective Having two kinds of young, as certain annelids.
• adjective Producing only two eggs for a clutch, as certain birds do.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective zoology Having two kinds of young.
• adjective zoology Producing only two eggs in a clutch.